Compatibility of Azospirillum brasilense and Pseudomonas fluorescens in growth promotion of groundnut ( Arachis hypogea L)

ABSTRACT We attempted to study the compatibility among plant beneficial bacteria in the culture level by growing them near in the nutrient agar plates. Among all the bacteria tested, Rhizobium was found to inhibit the growth of other bacteria. From the compatible group of PGPR, we have selected one biofertilizer (Azospirillum brasilense strain TNAU) and one biocontrol agent (Pseudomonas fluorescens strain PF1) for further studies in the pot culture. We have also developed a bioformulation which is talc powder based, for individual bacteria and mixed culture. This formulation was used as seed treatment, soil application, seedling root dip and foliar spray in groundnut crop in vitro germination conditions. A. brasilense was found to enhance the tap root growth and P. fluorescens, the lateral root growth. The other growth parameters like shoot growth, number of leaves were enhanced by the combination of both of the bacteria than their individual formulations. Among the method of application tested in our study, soil application was found to be the best in yielding better results of plant growth promotion.

Compatibility of Azospirillum brasilense and Pseudomonas fluorescens in growth promotion of groundnut ( Arachis hypogea L.).

We attempted to study the compatibility among plant beneficial bacteria in the culture level by growing them near in the nutrient agar plates. Among all the bacteria tested, Rhizobium was found to inhibit the growth of other bacteria. From the compatible group of PGPR, we have selected one biofertilizer (Azospirillum brasilense strain TNAU) and one biocontrol agent (Pseudomonas fluorescens strain PF1) for further studies in the pot culture. We have also developed a bioformulation which is talc powder based, for individual bacteria and mixed culture. This formulation was used as seed treatment, soil application, seedling root dip and foliar spray in groundnut crop in vitro germination conditions. A. brasilense was found to enhance the tap root growth and P. fluorescens, the lateral root growth. The other growth parameters like shoot growth, number of leaves were enhanced by the combination of both of the bacteria than their individual formulations. Among the method of application tested in our study, soil application was found to be the best in yielding better results of plant growth promotion.

Efecto biofertilizante del preparado: residuos vegetales - bacteria nativa diazótrofa, sobre las variables biométricas en plántulas de Rhapanus sativus / Biofertilizer effect of the prepared from vegetales wastes - diazotroph native bacterium on biometrics variables of Rhapanus sativus seedlings

El uso de bioinoculantes a base de microorganismos con potencial biofertilizante representa una alternativa económicamente viable y de producción limpia para el sector agrícola. El objetivo del presente trabajo fue evaluar el efecto biofertilizante de un preparado elaborado con residuos sólidos vegetales (RSV) procedentes del mercado y la bacteria nativa diazótrofa Azotobacter A15M2G. Se elaboraron biopreparados utilizando diferentes concentraciones de bacteria (106, 107 y 108 UFC) en un medio de cultivo obtenido a partir del 25% p/v de cada uno de los siguientes RSV: Brassica oleracea (repollo), Lactuca sativa (lechuga) y Allium fistulosum (cebollín). Los biopreparados fueron evaluados en plantas de rábano (Rhapanus sativus) en invernadero, utilizando un diseño estadístico completamente al azar de 5 tratamientos con 3 repeticiones: T1, control; T2, semillas pregerminadas tratadas con RSV al 25% p/v; T3, semillas pregerminadas con bioinoculante de 106 UFC; T4, semillas pregerminadas con bioinoculante de 107 UFC; T5, semillas pregerminadas con bioinoculante de 108 UFC. Se evaluó: número de hojas, área foliar, longitud de la planta, longitud de la raíz y peso seco de toda la planta (ensayos por triplicado). Se observó un incremento altamente significativo en peso seco para T5 (0,88 g) y T4 (1,10 g); y diferencias significativas en el área foliar, para los mismos tratamientos, con un valor superior a 2000 cm2. El biopreparado con bacterias nativas y RSV mejoró el crecimiento y desarrollo de las plantas de rábano, pudiéndose dar un valor agregado a estos residuos y de esta manera obtener un biofertilizante potencialmente utilizable en otros cultivos.

The use of bioinoculantes from microorganisms with biofertilizer potential, represents an economically viable alternative and of clean production for the agricultural sector. The aim of this study was to evaluate the effect of biofertilizer preparation obtained from vegetable solid waste (RSV) of the market and the native bacteria Azotobacter A15M2G diazotroph.Biological cultures were prepared using different inoculum concentrations, 106, 107 y 108 UFC in a culture medium obtained from 25% w / v of each of the following substrates: Brassica oleracea (cabbage), Lactuca sativa (lettuce) and Allium fistulosum (chives). The microbial inoculants were evaluated in radish plants (Rhapanus sativus) in greenhouse using a completely randomized design of 5 treatments with 3 replicates: T1, pre-germinated seeds without any treatment; T2, pre-germinated seeds treated with the dye waste vegetables 25% w / v; T3, pre-germinated seeds treated with bacterial concentration bioinoculants to 106 UFC; T4, pre-germinated seeds treated with bacterial concentration bioinoculants to 107 UFC, and T5, pre-germinated seeds treated with bacterial concentration bioinoculants to 108 UFC. Assessed variables were: number of leaves, leaf area, plant length, root length and dry weight of the entire plant (all assays in triplicate). The results showed a highly significant increase in dry weight, for T5 (0.88 g) and T4(1.10 g); and significant differences in leaf area for the same treatments, with a value greater than 2000 cm2, compared to others. The biopreparado from native bacteria and RSV improved the growth and development of the radish plants, being able to give a added value to these residues and to obtain a potentially usable biofertilizer in other cultures.

Micropropagation of photinia employing rhizobacteria to promote root development.

An alternative protocol was developed for in vitro propagation of photinia (Photinia x fraseri Dress), an ornamental shrub, using the plant growth-promoting rhizobacteria (PGPR) Azospirillum brasilense and Azotobacter chroococcum during rhizogenesis. Shoot tips from four-year-old mature plants, cut in spring and summer, were used as initial explants. They were cultured on Murashige-Skoog (MS) medium with Gamborg's vitamins, N(6)-benzyladenine (BA: 11.1 microM) and gibberellic acid (GA(3): 1.3 microM), obtaining 63% of established explants. The highest shoot length (22.9 mm) and multiplication rate (4.3) was achieved by cultivating for four weeks in the same basal medium supplemented with 4.4 microM BA. Both auxin induction and bacterial inoculation were used for rooting. Elongated shoots were treated with two concentrations of indole-3-butyric acid (IBA: 4.9 or 49.2 microM) during 6 days for auxin induction. Then, the shoots were transferred to an auxin-free medium and inoculated with A. brasilense Cd, Sp7 or A. chroococcum (local strain). Bacterial inoculation induced earlier rooting of photinia shoots. A. brasilense Cd with 49.2 microM IBA pulse showed a significant increase (P

[Encystment using different carbon substrates in Azotobacter chroococcum]. / Enquistamiento con distintos sustratos carbonados en Azotobacter chroococcum.

Carbon nutrition has a fundamental role in the encystment of bacteria of the genus Azotobacter. The effect of liquid media with various organic carbon substrates on the encystment of 2 strains of Azotobacter chroococcum was studied. Both strains had been previously cultured in a glucose and mannitol liquid medium. Strain 2087 showed the greatest degree of encystment (78%) with isopropanol and a very low percentage of cyst formation in the glucose and mannitol medium. In strain 1847 an important percentage of cyst formation (33%) was obtained in the glucose and mannitol medium and no cysts appeared with isopropanol. N-butanol and N-propanol induced in both strains relatively reduced percentages of encystment. The differential response found in the glucose and mannitol medium and the isopropanol media with strains 2087 and 1847 of A. chroococcum, has a degree of similarity in the different intensity of encystment shown by diverse strains of A. vinelandii with certain carbon substrates.